Carol Renaud/AFP/Getty Images(CHICAGO) -- An American who helped plan a terror attack that killed more than 160 people, including six Americans, has been sentenced to 35 years in federal prison.

David Headley, an American citizen of half-Pakistani descent, was convicted of conducting scouting missions that helped 10 men from Pakistan's Lashkar-e-Taiba terror group armed with grenades and automatic rifles mount a multi-day assault in Mumbai, India in November 2008. The terrorists attacked a train station, a luxury hotel and a Jewish center, killing 164 people and wounding hundreds more.

"Mr. Headley is a terrorist," said Judge Harry Leinenweber in imposing the sentence in a Chicago courtroom Thursday. "I don't have any faith in Mr. Headley when he says he's a changed person and believes in the American way of life."

Headley faced life imprisonment for his role but in a plea deal prosecutors agreed to seek a lesser sentence because of Headley's cooperation with their investigation. The government also agreed not to extradite him to India.

Headley, now 52, admitted that he attended training camps in Pakistan operated by Lashkar-e-Taiba five times between 2002 and 2005. He conducted five surveillance trips to Mumbai between 2006 and 2008 prior to the attack, and changing his name from Daood Gilani to David Headley so he would arouse less suspicion in India. Headley was also convicted of conspiracy for helping plot an attack on a Danish newspaper that had published a satirical cartoon of the Prophet Muhammad.

Headley was arrested at Chicago's O'Hare Airport on Oct. 3, 2009 en route to Pakistan. He intended to provide surveillance videos of the newspaper offices in Copenhagen to two co-defendants.

"Today's sentence is an important milestone in our continuing efforts to hold accountable those responsible for the Mumbai terrorist attacks and to achieve justice for the victims," said Lisa Monaco, Assistant Attorney General for National Security.

The Mumbai attackers arrived by boat on November 26, 2008 at landing sites scouted by Headley and attacked the Taj Mahal and Oeroi hotels, the Leopold Café, a train station and the Chabad House, a Jewish religious center. All the targets had been scouted by Headley.

Coleman, then known as Daood Gilani, had served time for heroin smuggling in the late 1990s. His sentence was lowered because he provided information about drug contacts in Pakistan. He traveled to Pakistan as an informant for the Drug Enforcement Administration, conducting undercover surveillance.